Catheterization and interventional procedures, such as angioplasty or stenting, generally are performed by inserting a hollow needle through a patient's skin and intervening tissue into the vascular system. A guidewire may then be passed through the needle lumen into the patient's blood vessel accessed by the needle. The needle may be removed, and an introducer sheath may be advanced over the guidewire into the vessel, e.g., in conjunction with or subsequent to a dilator. A catheter or other device may then be advanced through a lumen of the introducer sheath and over the guidewire into a position for performing a medical procedure. Thus, the introducer sheath may facilitate introducing various devices into the vessel, while minimizing trauma to the vessel wall and/or minimizing blood loss during a procedure.
Upon completing the procedure, the devices and introducer sheath are removed, leaving a puncture site in the vessel wall. External pressure may be applied to the puncture site until clotting and wound sealing occur. This procedure, however, may be time consuming and expensive, requiring as much as an hour of a physician or assistant's time. It is also uncomfortable for the patient and requires that the patient remain immobilized in the operating room, catheter lab, or holding area. Additionally, a risk of a hematoma exists from bleeding before hemostasis occurs. Accordingly, it can be desirable to seal the puncture using other techniques.
It can also be desirable to seal openings within a subject's body in other contexts as well. For example, in some instances it can be desirable to seal a fallopian tube to provide a form of birth control or disease prevention. It can also be desirable to seal openings that form in a body related to a defect or disease. Still further, in some instances it may be desirable to promote a flow of fluid through an opening, such as attaching a graft to a blood vessel. However, each of these techniques can be complicated by the limited nature of the space in which the procedures are to be performed and the devices and methods that currently exist for practicing such techniques.
By way of non-limiting example, one repair that is ripe for improvement is the treatment of a leaking mitral valve. The mitral valve includes two leaflets (anterior and posterior) attached to a fibrous ring or annulus. Contraction of the left ventricle in a healthy heart results in the mitral valve leaflets overlapping during contraction and prevention of blood flowing back into the left atrium. As a result of various medical cardiac diseases, the mitral value annulus may be come distended, causing the leaflets to remain partially open during ventricular contraction and thus allowing regurgitation of blood into the left atrium. In response to a reduced ejection volume from the left ventricle, the left ventricle tries to compensate with a large stroke volume. Eventually this increased workload results in dilation and hypertrophy of the left ventricle, further enlarging and distorting the shape of the mitral valve. The end result of this cardiac insufficiency if left untreated may be left ventricle failure and death. Current methods that exist for treatment of such conditions are limited.
Various apparatuses have been suggested for percutaneously sealing openings such as vascular punctures by occluding the puncture site, as well as for sealing other openings in a subject's body. One apparatus that exists for vascular closure is a biodegradable plug that is delivered through an introducer sheath into a puncture site. When deployed, the plug seals the vessel and provides hemostasis. Such plugs, however, may be difficult to position properly with respect to the vessel. Moreover, it is generally undesirable to expose the plugged material, e.g., collagen, to the blood stream where it may float down stream and risk causing an embolism. Another technique involves percutaneously suturing an opening. Percutaneous suturing devices, however, require significant skills by the user and can be mechanically complex and expensive to manufacture.
Other closure devices include surgical fasteners. One known surgical fastener includes an annular base having legs that, in a relaxed state, extend in a direction substantially perpendicular to a plane defined by the base and slightly inwards toward one another. During use, the fastener is fit around the outside of a cannula, thereby deflecting the legs outward. The cannula is placed in an incision, and the fastener is slid along the cannula until the legs pierce into the blood vessel. When the cannula is withdrawn, the legs move towards one another and back to the relaxed state to close the incision. Staples can also be used to close a wound or incision. Staples, however, tend to have a large cross-sectional profile and therefore may not be easy to deliver through a percutaneous site to close an opening in a vessel wall.
Accordingly, improved methods and devices for closing openings, including vascular puncture wounds, naturally existing openings in a subject's body, openings that result from defects or diseases, and surgically created openings, are needed. Improved methods and devices for promoting the flow of fluid through openings are also desirable.